How about this plugin (link)?
Seems pretty simple and to the point. It should allow for round times up to 346 minutes, however I'm not quite sure why that exact value was chosen.Code:#include <sourcemod> public OnPluginStart() { new Handle:mp_roundtime = INVALID_HANDLE; mp_roundtime = FindConVar("mp_roundtime"); SetConVarBounds(mp_roundtime, ConVarBound_Upper, true, 346.0); }